{"database":"biostudies-literature","file_versions":[],"scores":null,"additional":{"submitter":["Matsumoto KI"],"funding":["Intramural NIH HHS"],"pagination":["2275-2287"],"full_dataset_link":["https://www.ebi.ac.uk/biostudies/studies/S-EPMC8080971"],"repository":["biostudies-literature"],"omics_type":["Unknown"],"volume":["80(5)"],"pubmed_abstract":["<h4>Purpose</h4>Spin-lattice relaxation rate (R<sub>1</sub> )-based time-domain EPR oximetry is reported for in vivo applications using a paramagnetic probe, a trityl-based Oxo71.<h4>Methods</h4>The R<sub>1</sub> dependence of the trityl probe Oxo71 on partial oxygen pressure (pO<sub>2</sub> ) was assessed using single-point imaging mode of spatial encoding combined with rapid repetition, similar to T<sub>1</sub> -weighted MRI, for which R<sub>1</sub> was determined from 22 repetition times ranging from 2.1 to 40.0 μs at 300 MHz. The pO<sub>2</sub> maps of a phantom with 3 tubes containing 2 mM Oxo71 solutions equilibrated at 0%, 2%, and 5% oxygen were determined by R<sub>1</sub> and apparent spin-spin relaxation rate ( R2*) simultaneously.<h4>Results</h4>The pO<sub>2</sub> maps derived from R<sub>1</sub> and R2* agreed with the known pO<sub>2</sub> levels in the tubes of Oxo71. However, the histograms of pO<sub>2</sub> revealed that R<sub>1</sub> offers better pO<sub>2</sub> resolution than R2* in low pO<sub>2</sub> regions. The SDs of pixels at 2% pO<sub>2</sub> (15.2 mmHg) were about 5 times lower in R<sub>1</sub> -based estimation than R2*-based estimation (mean ± SD: 13.9 ± 1.77 mmHg and 18.3 ± 8.70 mmHg, respectively). The in vivo pO<sub>2</sub> map obtained from R<sub>1</sub> -based assessment displayed a homogeneous profile in low pO<sub>2</sub> regions in tumor xenografts, consistent with previous reports on R2*-based oximetric imaging. The scan time to obtain the R<sub>1</sub> map can be significantly reduced using 3 repetition times ranging from 4.0 to 12.0 μs.<h4>Conclusion</h4>Using the single-point imaging modality, R<sub>1</sub> -based oximetry imaging with useful spatial and oxygen resolutions for small animals was demonstrated."],"journal":["Magnetic resonance in medicine"],"pubmed_title":["EPR-based oximetric imaging: a combination of single point-based spatial encoding and T<sub>1</sub> weighting."],"pmcid":["PMC8080971"],"funding_grant_id":["Z01 BC010476"],"pubmed_authors":["Matsumoto S","Ogawa Y","Matsumoto KI","Krishna MC","Chandramouli GVR","Devasahayam N","Kishimoto S","Subramanian S"],"additional_accession":[]},"is_claimable":false,"name":"EPR-based oximetric imaging: a combination of single point-based spatial encoding and T<sub>1</sub> weighting.","description":"<h4>Purpose</h4>Spin-lattice relaxation rate (R<sub>1</sub> )-based time-domain EPR oximetry is reported for in vivo applications using a paramagnetic probe, a trityl-based Oxo71.<h4>Methods</h4>The R<sub>1</sub> dependence of the trityl probe Oxo71 on partial oxygen pressure (pO<sub>2</sub> ) was assessed using single-point imaging mode of spatial encoding combined with rapid repetition, similar to T<sub>1</sub> -weighted MRI, for which R<sub>1</sub> was determined from 22 repetition times ranging from 2.1 to 40.0 μs at 300 MHz. The pO<sub>2</sub> maps of a phantom with 3 tubes containing 2 mM Oxo71 solutions equilibrated at 0%, 2%, and 5% oxygen were determined by R<sub>1</sub> and apparent spin-spin relaxation rate ( R2*) simultaneously.<h4>Results</h4>The pO<sub>2</sub> maps derived from R<sub>1</sub> and R2* agreed with the known pO<sub>2</sub> levels in the tubes of Oxo71. However, the histograms of pO<sub>2</sub> revealed that R<sub>1</sub> offers better pO<sub>2</sub> resolution than R2* in low pO<sub>2</sub> regions. The SDs of pixels at 2% pO<sub>2</sub> (15.2 mmHg) were about 5 times lower in R<sub>1</sub> -based estimation than R2*-based estimation (mean ± SD: 13.9 ± 1.77 mmHg and 18.3 ± 8.70 mmHg, respectively). The in vivo pO<sub>2</sub> map obtained from R<sub>1</sub> -based assessment displayed a homogeneous profile in low pO<sub>2</sub> regions in tumor xenografts, consistent with previous reports on R2*-based oximetric imaging. The scan time to obtain the R<sub>1</sub> map can be significantly reduced using 3 repetition times ranging from 4.0 to 12.0 μs.<h4>Conclusion</h4>Using the single-point imaging modality, R<sub>1</sub> -based oximetry imaging with useful spatial and oxygen resolutions for small animals was demonstrated.","dates":{"release":"2018-01-01T00:00:00Z","publication":"2018 Nov","modification":"2025-04-26T09:22:12.735Z","creation":"2022-02-09T17:49:04.787Z"},"accession":"S-EPMC8080971","cross_references":{"pubmed":["29582458"],"doi":["10.1002/mrm.27182"]}}